Electrical contacts for printed circuit boards



March 1966 o. G. SCHEUERMANN 3,239,792

ELECTRICAL CONTACTS FOR PRINTED CIRCUIT BOARDS Filed April 3, 1962 2 Sheets-Sheet 1 4 48 4a; 48 45g, m?

INVENTOR.

BY WW Mwch 3965 o. G. SCHEUERMANN 3, 3

ELECTRICAL CONTACTS FOR PRINTED CIRCUIT BOARDS Filed April 5, 1962 2 Sheets-Sheet 2 United States Patent 3,239,792 ELECTRECAL CONTACTS FOR PRINTED CIRCUIT BOARDS Otto Gregor Scheuermann, 1531 Railway Ava, Westfield, NJ. Filed Apr. 3, 1962, Ser. No. 184,810 6 Claims. (Ci. 33947) This invention relates to electrical contacts and more particularly to contacts which can be ganged or grouped in plurality so as to form a block of contacts carried on a printed circuit board, for connection to a similar block of contacts carried in another board or block.

It is an object of the invention to provide contacts which may be readily formed by conventional methods from metallic sheet material.

It is another object of the invention to provide contacts which will give tight resilient elongated face-to-face conductive connections.

It is still a further object of the invention to provide contacts which can mesh with other contacts identical thereto and effect a plurality of conductive contacting areas therewith.

It is a still further object of my invention to provide electrical contacts which are rugged and durable and which may be cheaply manufactured.

Other objects and features of my invention will be apparent in the following description:

Briefly, the invention contemplates manufacturing electrical contacts by blanking out individual contacts from a strip of resilient sheet metal such as phosphor bronze, beryllium-copper, brass, etc., wherein the blanking is devised to effect a fold in the stamped piece to provide a double thickness, thus effecting a very strong contact wherein certain edges of the double thickness are coined or pressure-formed so as to effect sharp linear elongated contact faces and lines. The contacts are so devised in certain instances so as to have slits, the edges of which interdigitate with the edges of slits of identical contacts to effect good, mechanical gripping and low-resistance passage of current from contact to contact. Other types of contacts disclosed herein are provided with tongues spaced in one way or another so as to interdigitate with tongues of identically shaped contacts to effect locked Contact engagement.

A detailed description of the invention now follows in conjunction with the appended drawing, in which:

FIG. 1 is an elevation of an electrical contact;

FIG. 2 is an end view thereof; taken on section -5;

FIG. 3 is a plan view of a portion thereof;

FIG. 4 represents an approximation of the actual size of the contact;

FIGS. 5, 6, 7, 8 and 9, show steps in the manufacture of contacts made in accordance with the general teaching of the contact of FIGS. 1-4;

FIG. 10 is a perspective of another type of contact of folded construction;

FIG. 11 shows a blank from which the contact of FIG. 10 is formed;

FIG. 12 is an end view of the contact of FIG. 10;

FIG. 13 is a side view of the contact of FIG. 10;

FIG. 14 is a fragmentary portion of the contact showing certain interlocking elements;

FIG. 15 illustrates the manner in which the contact may be applied to a printed circuit board.

The form of the invention shown in FIGS. 1 through 9 comprises formation of a contact from a single piece of suitable resilient metal wherein such contact comprises a body 43 from two spaced co-planar legs or cantilever tongues 45 extend, having an intermediate third cantilever tongue 48 struck therefrom and displaced side- 3,239,792 Patented Mar. 8, 1966 wise so that the inner surfaces of the tongues 45 and 48 are co-planar (see FIGS. 3 and 8). The beveled edges of the tongues are contact surfaces angularly related to each other approximately Thus, each tongue 45 has a surface 45a while tongue 48 has surfaces 48a as best seen on FIG. 8. Accordingly, if two identical contacts are oriented with respect to each other 180 they can be slid into engagement, facilitated by the front notching 52, provided to facilitate such engagement, and thereby electrical conduction between the four engaged pairs of surfaces will be effected, FIG. 7. In other words, each surface 48a will engage a respective surface 45a and since there are a total of four surfaces 48a between the two identical contacts, there will necessarily be four pairs of mating surfaces as shown in FIG. 9. Also, the sides 45b and 48b (FIG. 7) will effect contact, making a total of seven engaging surfaces between interdigitated contacts.

Other portions of the contact such as the struck-out lugs 55 may be fashioned at the time of forming the contact tongues as well as various connection and/or attachment means such as lugs 57 and the aperture 59, as well as a serrated edge 61 for digging into the surface of a printed circuit board. Lugs 55 may serve as retainers in the event of contact encapsulation.

The drawing, of course, is considerably magnified for the purpose of showing details. However, for relative comparison with an actual size contact, FIG. 4 illustrates an elevation similar to FIG. 1 but of the approximate size of a contact as contemplated for use in connection with printed circuit boards and other miniature electronics work, being usually to 1" long.

The mode of manufacturing the contact is generally indicated in FIG. 5 through FIG. 8. Thus, FIG. 5 shows the first step in forming the tongues, which is a coining operation, the coining grooves diverging at 62, FIG. 6, to give a broader and stronger connection of tongue 48 with body 43. FIG. 6 is a side view of such step, and in addition showing the cutting out of the entrance notches 52 which may occur at this time. FIGURE 7 shows the step in which the tongue 48 has been sheared from the tongues 45 and pressed outwardly therefrom, the surface 48b being co-planar with the surfaces 45!). FIG. 8 shows the final step wherein tongues 45 are moved nearer each other so that the beveled edges are related at 90 to each other; thus surfaces 45a are at 90 to each other and also at 90 with respect to the adjacent surfaces 48a. Likewise the surfaces 48a are at 90 to each other and of course at 90 with respect to the adjacent surfaces 45a. It will 'be noted that the spacing between adjacent surfaces 4511 and 48aat their mating corners is a mere fine slit 63 of the order of a few thousandths of an inch, thus a very tight resilient engagement is effected when identical contacts are slid into conductive relationshp as indicated in FIG. 9.

Referring now to FIG. 10, the modification therein is generally similar to that hereinabove discussed except that in this instance the walls 103 and 196 of the contact are folded on the line 109 and are in contiquity with each other so that the cantilevers tongue 112 extending from wall 103 and the two spaced cantilever tongues 115 extending from wall 106 have faces which are in a common plane. Thus, inwardly facing area 118 of tongue 112 is in a plane with the outwardly facing areas 121 of tongues 115. Tongue 112 is beveled at its top and bottom edges 124 while tongues 115 are oppositely beveled at edges 127. Wall 10 3 is provided with serrations, such at 130, and wall 106 is provided with a single depending tongue or lug 133.

Referring to FIG. 11, the blank from which the contact is folded is shown and it will be readily apparent how the contact is formed therefrom.

Referring to FIG. 13, it will be noted that the ends of various tongues are curved as at 136 and 139 so that a contact identical to that disclosed may engage therewith by interdigitation of tongue-s, thus effecting four shoulders of contact, namely, the two shoulders 124 and two shoulders 127. In other words, referring to FIG. 12, tongue 112 of the coacting contact would go into the space 142 when the tongues are interdigitated.

Preferably, the tongues are provided with stamped-out protuberances such as 145, the stamping-out of which leaves depressions such as 148 whereby when the tongues are interdigitated, they are locked with respect to each other by virtue of the protuberances snapping into corresponding depressions. As shown in 14, the protuberances and corresponding depressions are shown as they appear in a plan view of the lower tongue 115.

FIG. 15 illustrates the contact of FIG. 13 applied to the printed circuit board.

The contacts described hereinabove may be made by conventional coining, stamping, slitting and pressing methods, etc., as heretofore known in conjunction with the manufacture of items of resilient metals.

It will be apparent that the structures shown may be designed in various ways; for example, the fine slits provided in the invention, as disclosed in FIG. 1, may be gapped as desired, although I prefer a gap of .001 inch. In fact, the slit edges can be contiguous if desired, the entrance notches providing for ready meshing of identical contacts, wherein pushing the contacts together spreads the respective slits to whatever extent may be necessary, although the gap thus effected would normally be very small.

Further, it should be noted that the general V-shape bodies of manycf the structures disclosed are of particular advantage in adding to the gripping engagement of the contact faces due to the inherent resiliency of such shapes. For the same reason, such resiliency compensates for possible manufacturing inaccuracies of the slits themselves, since the flanges can give in order to permit conductiveengagement of the contact faces of imperfectly matched slits.

What is claimed is:

1. An electrical contact comprising a body of resilient metallic material having a portion with a tongue struck therefrom and separated therefrom, whereby the opposite surfaces of said tongue and said body are substantially coplanar and form contact faces, said tongue having elongated edge surfaces forming contact faces, said body having an open ended slot therein by virtue of said tongue being pressed outwardly thereof, said slot having elongated surfaces forming contact faces, said contact faces of said tongue being angularly related to each other and said contact afces of said slot being angularly related to each other, said edges being beveled with respect to said surfaces whereby the beveled edges of opposed contacts are complementary to one another and an electrical contact of identical configuration may be interdigitated endwise with said described electrical contact so that the tongue of each contact is disposed in the slot of the other with the contact faces of said tongues and slots in conductive engagement.

2. An electrical contact comprising a body of resilient metallic material having an extending cantilever tongue means affording two longitudinally disposed conductive side contact surfaces and having a second tongue means extending parallel to said first tongue means and having respective conductive side contact surfaces disposed with respect to said first mentioned contact surfaces so that identical contacts may be interdigitated to effect engagement of respective surfaces of the first and second tongue means, said second tongue means being offset from said body in a direction normal to said surfaces, each of said tongue means having respective longitudinal beveled edges angularly related to all said first mentioned surfaces and being of complementary disposition so as to effect wedging edge engagement of tongues of interdigitated identical contacts.

3. An electrical contact as set forth in claim 2, wherein said second tongue means is offset from said body by virtue of being struck therefrom.

4. An electrical contact as set forth in claim 2, wherein said second tongue means is offset from said body by virtue of a fold line parallel to said tongue means.

5. In an electrical contact as set forth in claim 2, said second tongue means having a surface substantially in the plane of the surfaces of said first mentioned tongue means.

'6. An electrical contact comprising an integral body of resilient metallic material having a pair of parallel longitudinally extending cantiliver tongues having surfaces in substantialy the same plane wherein said surfaces are disposed for electrical engagement with correspond ing surfaces of an interdigitated identical contact, and also having an opposed cantilever tongue offset transversely from said first-mentioned tongues and having a surface in said plane and disposed for electrical contact engagement with a corresponding surface of said identical contact, said pair of tongues being spaced to receive therebetween the opposed tongue of said identical contact, said pair of tongues and said opposed tongue having additional surfaces for electrical contact engagement comprising edges disposed for substantially the length thereof engageable with respective edges of the tongues of said identical contact, said edges being beveled with respect to said surfaces whereby the beveled edges of opposed contacts are com plementary to one another effecting a transverse wedging force component when two identical contacts are interdigitated.

References Cited by the Examiner UNITED STATES PATENTS 2,125,816 8/1938 Reynolds 339-47 2,497,523 2/ 1950 Warkenstein 339-47 2,554,876 5/1951 Olson 339-47 2,559,943 7/1951 Cerny 339-258 X 2,713,154 7/1955 Bilsborough 339-47 2,750,572 6/1956 Fox 339-47 X 2,762,022 9/1956 Benander et a1. 339-47 2,785,387 3/1957 Batcheller 339-258 2,946,976 7/1960 Blain 339-17 3,011,143 11/1961 Dean 339-49 3,079,578 2/1963 Swengel 339-17 FOREIGN PATENTS 675,587 7/1952 Great Britain.

OTHER REFERENCES Ruehlemann: Electric Industries, December, 1958, page 51.

JOSEPH D. SEERS, Primary Examiner. 

2. AN ELECTRICAL CONTACT COMPRISING A BODY OF RESILIENT METALLIC MATERIAL HAVING AN EXTENDING CANTILEVER TONGUE MEANS AFFORDING TWO LONGITUDINALLY DISPOSED CONDUCTIVE SIDE CONTACT SURFACES AND HAVING A SECOND TONGUE MEANS EXTENDING PARALLEL TO SAID FIRST TONGUE MEANS AND HAVING RESPECTIVE CONDUCTIVE SIDE CONTACT SURFACES DISPOSED WITH RESPECT TO SAID FIRST MENTIONED CONTACT SURFACES SO THAT IDENTICAL CONTACTS MAY BE INTERDIGITATED TO EFFECT ENGAGEMENT OF RESPECTIVE SURFACES OF THE FIRST AND SECOND TONGUE MEANS, SAID SECOND TONGUE MEANS BEING OFFSET FROM SAID BODY IN A DIRECTION NORMAL TO SAID SURFACES, EACH OF SAID 